1. Technical Field
The present invention relates to an optical position detection apparatus optically detecting the position of a target object and an appliance having a position detection function provided with the optical position detection apparatus.
2. Related Art
An optical position detection apparatus optically detecting a target object has been proposed, in which, for example, a first light source unit and a second light source unit emit detection light toward the target object, and a light receiving unit detects the detection light that is reflected from the target object. According to this optical position detection apparatus, the position of the target object can be detected based on a comparison result of light intensities in the light receiving unit when the first light source unit and the second light source unit are sequentially turned on and a comparison result of the drive current when the first light source unit and the second light source unit are controlled so that the light intensities in the light receiving unit become equal to each other in a case where the first light source unit and the second light source unit are sequentially turned on (for example, see JP-A-2003-534554).
The optical position detection apparatus described in JP-A-2003-534554 detects the position of the target object by using the relationship between the emission intensity of the detection light from a plurality of light source units and the light intensity in the light receiving unit. Accordingly, if there is a difference in the relationship between the drive current and the emission intensity in the light source unit or if there is a difference in the relationship between the incident light quantity and the signal intensity in the light receiving unit, the detection accuracy is deteriorated. Accordingly, in the optical position detection apparatus, it is necessary to appropriately perform initial setting of the relationship between the drive current of the light source units and the light intensities in the light receiving unit. Further, in the optical position detection apparatus, it is preferable to appropriately perform the initial setting of the relationship between the drive current and the light intensity whenever the optical position detection apparatus starts operation.
However, since JP-A-2003-534554 fails to describe the necessity of the initial setting as described above, the technique described in JP-A-2003-534554 has a problem in that it is difficult to constantly set an appropriate condition with respect to the relationship between the drive current and the light intensity.
In FIG. 1 of JP-A-2003-534554, a light transmissive member is arranged on the front side of the first light source unit, the second light source unit, and the light receiving unit, and if the first light source unit and the second light source unit are turned on in conditions where a target object is present, the light that is reflected by the light transmissive member is also incident to the light receiving unit together with the light that is reflected by the target object. However, JP-A-2003-534554 fails to describe that a default light is incident to the light receiving unit through turning on the first light source unit and the second light source unit in a state where the target object is not present or the relationship between the drive current and the light intensity is initially set based on the result of receiving the default light in the light receiving unit.